JP6424396B2 - Multiple access scheme and signal structure for D2D communication - Google Patents

Description

  RELATED APPLICATIONS This application claims the benefit of priority to US Provisional Application 61 / 624,185, filed April 13, 2012, which is filed on Dec. 28, 2012. , 164 claim the benefit of priority. Both of them are incorporated herein by reference in their entirety.

  Device-to-device (D2D) communication is one means to improve the performance of Long Term Evolution (LTE) and other cellular networks. In D2D communication, multiple terminals (referred to as user equipment or UEs in LTE) are directly linked with each other rather than being linked via a base station (referred to as evolved Node B or eNB in LTE) connect. D2D communication between two or more D2D devices is typically very local and uses very low transmit power due to the short distance between multiple D2D devices. D2D communication is also an effective way to increase spatial reuse in multiple cellular systems because of higher throughput.

  One approach to D2D communication as a foundation of the LTE network infrastructure is an out-of-band solution. In out-of-band solutions, D2D traffic is unloaded against unlicensed bands on the application layer (eg, Wi-Fi® as defined in the IEEE 802.11 standard). Another approach is an in-band solution. In the in-band solution, multiple D2D transmissions occur in the same licensed band being used by the LTE network. The present disclosure addresses aspects of the in-band approach to D2D communication. In particular, the focus is on signal structures to support in-band D2D communication, scheduling of multiple D2D transmissions, and power control for interference management.

7 shows an example of a UE device and an eNB for D2D communication.

2 illustrates a signal structure for D2D communication in one embodiment.

7 illustrates the operation of AGC in a D2D receiver in one embodiment.

17 illustrates an example of an algorithm processed by a D2D receiver when accessing a channel via CSMA.

Fig. 6 shows an example of numbering used for distributed D2D slots in time and frequency.

FIG. 7 illustrates the problem of CSMA when the transmit power is different among multiple D2D devices.

Figure 7 illustrates the operation of an autocorrelation bank to detect transmit power from a preamble.

  The following description and the drawings sufficiently show specific embodiments so that those skilled in the art can carry them out. Other embodiments may incorporate structural, logical, electrical, process, and other variations. Parts and features of some embodiments may be included in other embodiments or may be included in place of those of other embodiments. The embodiments set forth the claims include all available equivalents of the claims.

  FIG. 1 shows an example of a UE 10 and a UE 20 each including a processor 21 coupled to a radio frequency (RF) transceiver circuit 22 connected to one or more antennas 23. The base station or eNB 40 is shown with a processor 41 coupled to an RF transceiver circuit 42 connected to a plurality of antennas 43. The illustrated configurations provide any type of hardware / software configuration to provide multiple air interfaces for both LTE and D2D communication, and to perform the processing functions described herein. It is intended to represent. In the illustrated embodiment, both of the plurality of UEs 10 and 20 communicate with the eNB 40 over the plurality of LTE links and over the D2D link.

  The physical layer of LTE is based on Orthogonal Frequency Division Multiplexing (OFDM) for downlink and related techniques and based on Single Carrier Frequency Division Multiplexing (SC-FDM) for uplink. In OFDM / SC-FDM, a plurality of complex modulation symbols are individually transmitted between OFDM / SC-FDM symbols, referred to as resource elements (REs), according to a modulation scheme such as QAM (Quadrature Amplitude Modulation) Are mapped to specific OFDM / SC-FDM subcarriers. RE is the smallest time frequency resource in LTE. In LTE, multiple layers of data are transmitted and received by multiple antennas, and each of a plurality of complex modulation symbols is mapped to one of the multiple transmission layers and mapped to a specific antenna port. It also provides input multiple output) operation. Each RE is then uniquely identified by the antenna port, subcarrier position, and OFDM / SC-FDM symbol index in the radio frame. Multiple LTE transmissions in the time domain may be combined into multiple radio frames, each having a duration of 10 ms. Each radio frame consists of 10 subframes, and each subframe consists of 2 consecutive 0.5 ms slots. Each slot comprises 6 indexed OFDM symbols for the extended cyclic prefix and 7 indexed OFDM symbols for the standard cyclic prefix. Groups of resource elements corresponding to 12 consecutive subcarriers in a single slot are referred to as resource blocks (RBs) or physical resource blocks (PRBs) with respect to the physical layer. Each PRB pair consists of two consecutive slots in time.

For FDD (frequency division duplex) operation, separate carrier frequencies are provided for uplink and downlink transmission, and the above frame structure is applicable to both uplink and downlink without modification. . In TDD (time division duplex) operation, either uplink or downlink transmission, as well as special subframes that occur on the downlink to uplink transmission transition (as opposed to the uplink to downlink transmission transition) Also, a plurality of subframes are allocated. The eNB manages allocation of multiple uplink and downlink subframes in each radio frame during TDD operation.
[D2D signal structure]

  For in-band D2D communication, multiple UEs operating as multiple D2D devices may communicate using multiple time frequency resources assigned by the eNB to the D2D link. The timing and synchronization is then performed as in a regular LTE link, and each D2D device synchronizes its clock and symbol / slot boundaries with the eNB as a regular UE. As D2D communication is usually within a short distance, the propagation times from the same eNB to multiple communicating D2D devices should be approximately the same. More precisely, the difference between the two timings (e.g. the boundaries of symbols) of the communicating D2D pair should be about 0.2-1 [mu] s. It is within the cyclic prefix range of OFDM or SC-FDM and eliminates the need for additional synchronization mechanisms. Timing and frequency synchronization can be achieved as in conventional systems, but there are further additional aspects for D2D communication. There may be different eNBs, such as macro eNBs and pico eNBs, used in areas of multiple D2D devices. ENBs from different operators may not be synchronized with one another or may have the same OFDM symbol duration. Thus, time and / or frequency references to multiple communicating D2D devices must be identified. For example, multiple communicating D2D devices are associated with the same eNB, which identifies an eNB, eg, macro or pico eNB, for synchronization. In addition to timing and frequency synchronization, several other physical and MAC layer parameters such as carrier frequency, bandwidth, cyclic prefix length, group ID, and D2D frequency time resources are all eNB or D2D It needs to be identified by the coordinator or D2D group owner. There are two modulation options for D2D data modulation, OFDM and SC-FDM, using multiple time frequency resources allocated by the eNB. These are respectively used for downlink and uplink in a normal LTE device. The two schemes share most of several hardware configurations, such as those for performing FFT (Fast Fourier Transform) and IFFT (Inverse Fast Fourier Transform). Although SC-FDM is comparable to OFDM in terms of high PAPR (peak-to-average power ratio), it may still be desirable to use OFDM for D2D. First, since D2D communication is for short range, its peak power should be much smaller than that of normal uplink transmission. Second, SC-FDM is vulnerable to inter-symbol interference (ISI) but OFDM is not. Third, channel training overhead is smaller for OFDM than for SC-FDM.

  A channel training signal is required for the D2D receiver to demodulate the received signal. The existing multiple reference signal (RS) patterns used in LTE, such as UE-RS or DM-RS, may also be used to reduce the complexity of UEs configured also for multiple D2D operations. , May be used for D2D. However, multiple channel characteristics, such as multipath delay and time change, are quite different for D2D links compared to typical LTE links. Multiple D2D devices are typically indoors and experience less mobility and delay spread than regular multiple UEs. Thus, the RS density for the D2D link may be smaller than that of a normal cellular link, and reducing RS density improves throughput. Since either OFDMA or SC-FDM can be used for D2D communication, somewhat different channel training designs can be used for each. For OFDM, the channel training signal should be a set of multiple reference subcarriers and may be a subset of the existing RS pattern. For example, for regular LTE RBs, only the existing RSs in the first slot of the PRB pair may be used for channel training, with RSs in the second slot used for data. it can. In addition, different RS patterns may be used while utilizing subsets from existing RSs. For example, RS subcarriers may be located only in the first OFDM symbol of a PRB pair to reduce channel estimation latency and channel training overhead. For SC-FDM, the channel training signal should be one or many reference symbols that exclusively occupy the sub-band or frequency band of the PRB during the symbol duration. Again, fewer RSs in the regular LTE uplink RB may be used for the D2D link, eg, the second RS symbol in the RB may be replaced by a data symbol.

  In normal LTE communication, the UE only communicates with the eNB on both downlink and uplink. This allows both timing and power levels to be controlled via various control channel signals between the eNB and the UE, such as ranging and power control feedback. The situation is different in the case of distributed D2D. Because one D2D device may receive multiple signals from different D2D devices, the received power typically varies from device to device. When the UE receives a signal on a radio frequency (RF) carrier, the signal is downconverted to baseband, amplified and digitized at an analog to digital converter (ADC) before being demodulated. However, accurate digitization of the received signal requires an amplification gain such that the resulting amplified signal falls within the proper range of the ADC. A short preamble may be placed at the beginning of transmission to set up the AGC. This short preamble should be located in the same frequency band or sub-band as the subsequent data signal. A short preamble may comprise multiple periods of the same signal in the time domain, and repetition of the same signal allows detection of the preamble via autocorrelation. The duration of the short preamble may for example be between 0.5 and 20 μs.

Due to the small payload size of multiple sensors, which are the main part of multiple D2D devices, one slot x one RB can be defined as a basic resource allocation unit, and in this specification D2D slots or D2D packets and It is called. For large payload sizes, the basic resource allocation unit can be 2 slots x 1 RB. An example of a signal structure for a D2D packet 200 incorporating the features described above for SC-FDM is shown in FIG. The following short preamble SP and reference signal RS are a plurality of SC-FDM symbols carrying control information or data, and a plurality of resources respectively mapped to a physical D2D control channel (PdCCH) or a physical D2D shared channel (PdSCH) Conveyed by the element. D2D packets for OFDM are similar, except that the reference signals are multiple specific resource elements distributed in time and frequency. The cyclic prefixes of OFDM or SC-FDM symbols may be shorter than those used in the cellular LTE link. FIG. 3 illustrates the operation of a D2D receiver that utilizes the short preamble of D2D packets. After receipt of the RF carrier signal by the RF transceiver 301, the resulting signal is downconverted to baseband by the downconverter 302, amplified by the amplifier 303, sampled and digitized by the ADC 305, and transmitted multiple times. It is demodulated by an OFDM / SC-FDM demodulator 306 to extract the symbols. Before digitization, the automatic gain control module 304 detects the short preamble at the beginning of the D2D packet and adjusts the gain of the amplifier 303 based on the power of the signal.
[Distributed schedule control]

  In the in-band approach to D2D communication, there are basically two other techniques for scheduling transmissions. One relies on the base station, eNB, to schedule and coordinate multiple D2D transmissions using multiple assigned time frequency resources. The other technology not only competes for multiple transmissions using multiple allocated time frequency resources, but relies primarily on the D2D device itself to manage any interference. The second technology is most suitable for multiple sensor networks, which typically have multiple small sized packets rather than large control overhead. For such small packets, scheduling and interference control by the eNB may not be efficient for at least two reasons. First, there may be eNBs that can not know the interference status between any two D2D links as a whole, as well as multiple D2D devices and links. And, even though the eNB can request the D2D device to report multiple measurements of interference, the system has large feedback overhead from these reports in scheduling many such D2D transmissions. Or it may not be able to handle large control overhead.

  In the techniques for distributed schedule control described herein, Carrier Sense Multiple Access (CSMA) is used in in-band D2D communication. CSMA not only achieves high spatial reuse but also reduces control overhead between D2D devices and eNBs. As described previously, multiple resources for D2D communication are allocated by the eNB. The eNB broadcasts resource assignments to groups of multiple D2D devices. The grouping of devices may be according to the quality of the channels between them. As explained above, resources may be divided into D2D slots or PRB pairs, and allocated D2D slots or groups of PRB pairs may be in time or / and in frequency. It may be collected or distributed in frequency and time. In one embodiment, each such D2D slot is used as a time slot for a slotted aloha type CSMA incorporating a backoff mechanism to reduce collision frequency. FIG. 4 illustrates the steps involved in an example algorithm for a D2D device that wants to transmit. At step 401, the device randomly selects a number N to begin the countdown. At step 402, the device detects the beginning of the next D2D slot. If the slot is busy, then in step 403 the countdown is suspended and step 402 is repeated. If the slot is not busy, then at step 404, N is decremented. If at step 405 it is determined that N has been decremented to zero, then at step 406 the device transmits in the next slot. Otherwise, the device returns to step 402. The plurality of D2D slots may be labeled in order of occurrence as shown in FIG. 5 such that a countdown of the plurality of slots in the backoff window is performed. The order of slots in FIG. 5 is frequency first to reduce delay and to account for half duplex operation of D2D devices.

In another embodiment, the transmitting D2D device may specify a reservation time in the PdCCH of the transmitted packet to indicate the length of time the device is transmitting. By detecting the reservation time specified in PdCCH, multiple D2D devices can skip the operation of carrier detection and go to sleep until the reservation time is over. This reduces the power consumption of multiple D2D devices. Also, another embodiment includes using an eNB if it is necessary to meet multiple requirements for latency, as the aloha type CSMA delay is not resolved. For example, if the D2D link can not transmit data out in time, the D2D device can request the eNB to transfer D2D data to the destination D2D device. This improves the latency of D2D traffic by using the eNB as a backup.
Power Detection and Control for Interference Management

  In the D2D system described above, multiple D2D devices may contend for channel access and transmit data to multiple other D2D devices. Because D2D devices may transmit data to different D2D devices at different distances, transmit power aims to reduce interference, increase spatial reuse, and improve power efficiency As it should be changed according to the transmission distance. In a D2D network with many nodes, Carrier Sense Multiple Access (CSMA) as described above is the most efficient method for channel access control. However, CSMA alone can not support fair access among multiple nodes with different transmit powers. The reason is that the device can not predict its interference level at another device using the received signal from normal carrier sensing. For example, as shown in FIG. 6, node C wants to transmit and does not want to interfere with existing multiple transmissions in communication. Node C performs carrier sensing and detects existing transmissions from node A to node B. In normal CSMA, if the received signal power detected from carrier sensing is below a certain threshold, node C should consider that channel as idle and may access that channel. However, as a premise here, the interference levels are interrelated between any transmitter and receiver pairs. If the receiver is receiving some level of interference from the transmitter, then the transmitter should receive the same level of interference when the original transmitter is listening to the transmitter of the original receiver. This relies on the fact that the radio channels are interrelated and the transmit power is constant among all nodes. However, this assumption is no longer true when the transmit power is diverse across multiple nodes. In the example of FIG. 6, node A and node B are close to each other, and node A uses low power to talk to node B. The resulting interference from node A to node C is small due to the reduced transmit power. Thus, if node C does not know that node A has reduced its transmit power, node C may start transmitting at full power to talk to node B.

  The solution to this problem involves identifying the transmit power level prior to transmission so that other nodes can predict the interference level. The transmit power level may be transmitted or broadcast in the (D2D) control channel by the transmitter or coordinator node. Instead of using a control channel that can include multiple types of control information, the transmit power level can be identified simply by the transmit power indicator added to the plurality of D2D packets. The prior specification of transmit power prior to actual transmission can be applied to CSMA and other types of media access such as distributed scheduling. This prior specification needs to be sent reliably, as the transmit power levels are for other nodes to predict the interference level if they cause multiple interference problems. For example, reliable encoding such as recurring or high power transmission, spreading, and channel code may be applied to broadcast transmit power levels. And, in carrier detection type of media access, a D2D receiver desiring to transmit may use transmission power information for transmission power estimation during carrier detection. In one embodiment, transmit power levels are signaled at the beginning of each transmit burst. The path loss can be estimated by subtracting the received signal power from the transmit power after the transmit power level is detected or estimated. Using the estimated path loss, the D2D receiver can determine whether it can transmit and which transmit power level should be used. Examples of techniques for transmitting transmit power indicators are described below.

  In one embodiment, multiple D2D packets with different transmit powers may be sent with different preamble sequences, which may be detected during carrier detection or channel estimation. As described above, D2D packet preambles may also be used to set adaptive gain control (AGC) or for channel estimation. For example, multiple short preambles with different durations (eg, 2 μs, 3 μs, or 5 μs) can be used to signal transmit power levels and to set the AGC. The receiver can have a bank of autocorrelators with different correlation periods (eg, 2 μs, 3 μs, or 5 μs) to detect the arrival of the signal and the transmit power level. FIG. 7 shows an example of an autocorrelation bank in a D2D receiver used to distinguish between 2 μs and 3 μs preamble periods. After receipt by the RF transceiver 301 and downconversion to baseband by the downconverter 302, multiple versions of the 2 μs and 3 μs delayed signals are generated by the delay elements 320 and 330, respectively. The delayed versions of the signal are then correlated with the undelayed signal by the correlators 310 and 311. The outputs of the correlators are then compared by the comparator 312 to detect the periodicity of the preamble.

  In another embodiment, when it is preferred to use multiple digital samples, instead of placing a transmit power indicator in the preamble sequence, a transmit power indicator (TPI) is placed in the channel training signal. Good. For example, TPI may be in multiple reference signals such as a single SC-FDM symbol used as RS in SC-FDM, or in different multiple resource elements used as multiple reference signals in OFDM It may be arranged. Different channel training sequences may be applied to each different transmit power level. Since the number of power levels may be between 4 and 8, only a small number of sequences may be required, with sequence detection errors negligible at the operating SNR of the data frame. For distributed multiple reference signals as in OFDM, transmit power can be detected during the entire D2D packet as compared to other alternatives. If the listener of the channel misses the beginning of the D2D packet, distributed reference signals can be used to later know about the transmit power.

  If the number of transmit power levels is relatively large, the previous approaches may lead to high error rates in sequence detection. In another embodiment to address this issue, the transmit power level can be signaled by multiple bits in the physical layer header. The physical layer header may follow a sequence for setting up an AGC, such as a short preamble. This reduces the carrier detection latency and the power consumption of the receiver. The receiver should decode multiple TPI bits from the header. The header may have multiple CRC check bits in order to verify multiple detected TPI bits. As explained above, in addition to the transmit power, the receiver may be involved in the duration of transmission to enable collision avoidance. Such duration information or channel reservation time may be in the header and may be implicitly specified by the system. In the example of implicit specification, the duration may always be one subframe for some systems.

In another embodiment, the transmit power level is signaled by channel reservation exchange prior to data block transmission. This is similar to the RTS / CTS channel reservation used in Wi-Fi, in cellular D2D, where other nearby D2D devices know about the reserved duration and transmit power within the duration As possible, channel reservations can be made by transmitters and receivers with default (high) power levels. As an alternative, the base station may broadcast channel reservation and transmit power levels to nearby D2D devices for the transmit pair.
[Example]

  In one embodiment, the UE receives multiple assignments of multiple time frequency resources for D2D communication from the wireless transmitter to provide an air interface for communicating with the eNB and for D2D communication, and A processing circuit connected to the wireless transmitter for establishing a D2D communication session with the second UE. When there are many eNBs, the processing circuit may establish, as the second UE, synchronization of timing and frequency with the same eNB. The plurality of resources or plurality of D2D transmissions to or from the second UE may be the same plurality of resource structures, as used in a cellular LTE link, or begin with a preamble and a plurality of OFDM / SC-FDM A plurality of D2D slots may be organized at each D2D slot containing a symbol. The cyclic prefix length of multiple OFDM / SC-FDM symbols may be shorter than those used in cellular LTE links. A processing circuit may downconvert and amplify the plurality of preambles of the plurality of D2D slots received prior to analog to digital conversion, and the plurality of preambles of the plurality of D2D slots received may be automatic gain control (AGC) Used for. If the time since the last transmission to the second UE is long enough that the AGC setting can be out of range, the processing circuit may use the preamble for AGC at the beginning of the data burst. The preamble may be a repetitive signal sequence in the time domain, and each D2D slot may include one or more reference symbols. The multiple channel training signals or multiple reference signals of the D2D slot may have a lower density than used in the cellular LTE link. The processing circuit may further detect the preambles of the received plurality of D2D slots via autocorrelation. The processing circuit may further detect the current D2D slot to determine if a transmit operation is present, and, if the current D2D slot is not busy, to the second UE at the start of the subsequent D2D slot. By transmitting D2D transmissions, carrier sense multiple access (CSMA) may be used for D2D slots to initiate a communication session with the second UE. The processing circuit may also start the countdown at the selected number if the current D2D slot is not busy, decrement the countdown after each non-busy D2D slot is detected, and the busy D2D slot A communication session with the second UE may be initiated by suspending the countdown when detected and transmitting a D2D transmission to the second UE at the start of the next D2D slot after the countdown reaches zero. The particular number for the countdown may be chosen randomly or pseudo-randomly. The D2D slot may further include an encoded reservation time in the control channel that specifies how many D2D slots are continuously transmitted by the transmitting device. The plurality of D2D slots may be numbered consecutively in the time and / or frequency domain. The processing circuit may also suspend detection of multiple D2D slots until the reservation time ends, when the reservation time is detected in the D2D slot. The processing circuit may also go to sleep until the reservation time ends, when the reservation time is detected in the D2D slot. The processing circuit may further transmit an indication of transmit power level in each D2D slot. The preamble may be a repetitive signal sequence in the time domain having a periodicity indicative of the transmit power level. The processing circuit may further comprise a bank of correlators having different correlation periods for detecting the arrival of preambles and transmit power levels.

  In another embodiment, the UE receives a plurality of allocations of time-frequency resources for radio communication for communicating with the eNB and providing an air interface for D2D communication, and for D2D communication from the eNB. , Processing circuitry connected to the wireless transmitter, establishing a D2D communication session with the second UE. The processing circuit may further transmit an indication of the transmit power level in the one or more reference symbols, and the identified reference symbol or identified sequence of reference symbols indicates the transmit power level. The transmit power level may be identified prior to actual data transmission to enable interference prediction when multiple transmit power levels co-exist. The processing circuit may further transmit an indication of transmit power level as a plurality of encoded bits in the physical layer header following the preamble. The physical layer header further constitutes a transport block and comprises an indication of the number of D2D slots transmitted continuously. The processing circuit may further receive, in response to the channel reservation request, a plurality of allocations of time frequency resources for D2D communication from the eNB, a transmission power level indicator for the D2D communication and a reservation of The duration is included in the channel reservation request. The channel reservation request may be sent at a power high enough to allow other UEs in proximity to the device to know the channel reservation and transmit power level.

  In another embodiment, the UE receives a plurality of allocations of time-frequency resources for radio communication for communicating with the eNB and providing an air interface for D2D communication, and for D2D communication from the eNB. Establishing a D2D communication session with the second UE, processing circuitry connected to the wireless transmitter, sensing a current D2D slot to determine if a transmit operation is present, and a current D2D When the slot is not busy, initiate a communication session with the second UE using Carrier Sense Multiple Access (CSMA) for the D2D slot by transmitting a D2D transmission to the second UE at the beginning of the subsequent D2D slot Thus, multiple D2D transmissions to and from the second UE may be multiple OFDM / SC-FDM They are grouped into a plurality of D2D slots in each D2D slots containing symbols. The processing circuit may also start the countdown at the selected number if the current D2D slot is not busy, decrement the countdown after each non-busy D2D slot is detected, and the busy D2D slot A communication session with the second UE may be initiated by suspending the countdown when detected and transmitting a D2D transmission to the second UE at the start of the next D2D slot after the countdown reaches zero. The particular number for the countdown may be chosen randomly or pseudo-randomly. The D2D slot may further include an encoded reservation time in the control channel that specifies how many D2D slots are continuously transmitted by the transmitting device. The processing circuit may also suspend detection of multiple D2D slots until the reservation time ends, when the reservation time is detected in the D2D slot. The processing circuit may also go to sleep until the reservation time ends, when the reservation time is detected in the D2D slot.

  Embodiments as described above may be implemented as a method for operation and / or in various hardware configurations including a processor for executing instructions to perform the method. Such instructions may be included on a suitable storage medium, from which it may be moved to memory or other processor executable medium.

  The subject matter was described in the context of LTE networks. The subject matter may be used in other types of cellular networks, with respect to UEs and eNBs replaced by reference to terminals and base stations, respectively, unless inconsistencies arise.

  The subject matter has been described in connection with the specific embodiments described above. It should be understood that these embodiments may also be combined in any way which is considered to be advantageous. Also, many alternatives, variations, and modifications will be apparent to those skilled in the art. Other such alternatives, variations, and modifications are intended to fall within the scope of the following appended claims.

A summary is provided in accordance with the US Patent Enforcement Regulations. Section 1.72 (b) requires an abstract allowing the reader to confirm the nature and spirit of the technical disclosure. It is submitted with the understanding that it is not used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the Detailed Description as individual embodiments of each claim on its own.
[Item 1]
A user equipment (UE) device,
a wireless transmitter providing an air interface for communicating with an eNB (Evolved Node B) and for D2D (Device to Device) communication;
Processing circuitry connected to the wireless transmitter;
The processing circuit
Receive multiple assignments of multiple time frequency resources for D2D communication from the eNB;
Establish a D2D communication session with the second UE,
Perform multiple automatic gain control (AGC) using multiple received D2D slot preambles,
A device wherein multiple D2D transmissions to and from the second UE begin with the preamble and are grouped into multiple D2D slots at each D2D slot that includes multiple OFDM or SC-FDM symbols.
[Item 2]
The device according to item 1, wherein the preamble is a repetitive signal sequence in time domain.
[Item 3]
The device according to claim 2, wherein the processing circuit further detects the preambles of a plurality of received D2D slots via autocorrelation.
[Item 4]
The device according to item 2 or 3, wherein each D2D slot comprises one or more reference symbols.
[Item 5]
The processing circuit further comprises
Detecting the current D2D slot to determine if there is a transmit operation, and, if the current D2D slot is not busy, D2D transmission to the second UE at the start of the subsequent D2D slot By sending
5. The device according to any one of items 2 to 4, which initiates a communication session with the second UE using Carrier Sense Multiple Access (CSMA) for D2D slots.
[Item 6]
The processing circuit further comprises
Starting the countdown with the selected number if the current D2D slot is not busy,
After each D2D slot not busy is detected, the countdown is decremented, and when the busy D2D slot is detected, the countdown is suspended, and the next countdown is reached after the countdown reaches zero. By transmitting the D2D transmission to the second UE at the start of the D2D slot,
The device according to item 5, initiating a communication session with the second UE.
[Item 7]
The device according to claim 6, wherein the specific number for the countdown is selected randomly or with pseudo-random numbers.
[Item 8]
The D2D slot further comprises an encoded reservation time in the control channel, specifying how many D2D slots are transmitted consecutively by the transmitting device, according to any one of items 5 to 7 device.
[Item 9]
9. The device according to item 8, wherein the processing circuit further suspends detection of a plurality of D2D slots until the reservation time ends, when a reservation time is detected in the D2D slot.
[Item 10]
10. The device according to item 9, wherein the processing circuit further sleeps when the reservation time is detected in the D2D slot until the reservation time ends.
[Item 11]
11. A device according to any of the claims 5-10, wherein the plurality of D2D slots are consecutively numbered in the time and / or frequency domain.
[Item 12]
12. The device according to any one of items 1 to 11, wherein the processing circuit further transmits an indication of transmit power level in each D2D slot.
[Item 13]
13. The device according to claim 12, wherein the preamble is a repetitive signal sequence in a time domain having a periodicity indicative of the transmission power level.
[Item 14]
14. The device according to claim 13, wherein the processing circuit further comprises a bank of correlators having different correlation periods for detecting the arrival of the preamble and transmit power level.
[Item 15]
The processing circuit further transmits the indication of transmission power level in one or more reference symbols, and a specified reference symbol or a specified sequence of reference symbols indicates the transmission power level. The device according to any one of items 12 to 14.
[Item 16]
16. The device according to any one of items 12 to 15, wherein the processing circuitry further transmits the indication of transmit power level as a plurality of encoded bits in a physical layer header following the preamble.
[Item 17]
17. The device according to item 16, wherein the physical layer header comprises a transport block and further comprising an indication of the number of D2D slots transmitted continuously.
[Item 18]
The processing circuit further receives, in response to a channel reservation request, a plurality of allocations of time frequency resources for D2D communication from the eNB, a transmission power level indicator and an indication of reservation for D2D communication. 18. A device according to any one of the preceding items, wherein a duration is included in the channel reservation request.
[Item 19]
19. The device according to item 18, wherein the channel reservation request is transmitted at a power high enough to allow other UEs in proximity to the device to know the channel reservation and transmission power level.
[Item 20]
A user equipment (UE) device,
A wireless transmitter providing an air interface for D2D (device-to-device) communication;
Processing circuitry connected to the wireless transmitter;
The processing circuit initiates a D2D communication session with the second UE using Carrier Sense Multiple Access (CSMA) in association with the D2D slot,
The plurality of D2D transmissions to and from the second UE are grouped into a plurality of D2D slots in each D2D slot including a plurality of OFDM or SC-FDM symbols,
The processing circuit further comprises
Detect the current D2D slot to determine if there is a transmit operation,
A device for transmitting D2D transmissions to the second UE at the beginning of a subsequent D2D slot, if the current D2D slot is not busy.
[Item 21]
The processing circuit further comprises
Starting the countdown with the selected number if the current D2D slot is not busy,
Decrementing the countdown after each D2D slot not busy is detected, and suspending the countdown when a busy D2D slot is detected, and of the next D2D slot after the countdown reaches zero. By transmitting the D2D transmission to the second UE at the start:
The device according to item 20, initiating a communication session with the second UE.
[Item 22]
22. The device according to item 21, wherein the specific number for the countdown is selected randomly or with pseudo random numbers.
[Item 23]
23. The device according to any one of items 20-22, wherein the D2D slot further comprises an encoded reservation time in the control channel, specifying how many D2D slots are transmitted consecutively by the transmitting device. .
[Item 24]
24. The device according to Item 23, wherein the processing circuit further suspends detection of a plurality of D2D slots until the reservation time ends, when a reservation time is detected in the D2D slot.
[Item 25]
25. The device according to item 24, wherein the processing circuit further goes to sleep until the reservation time ends, when the reservation time is detected in the D2D slot.
[Item 26]
A method of operating a user equipment (UE) device, the method comprising:
Receiving multiple assignments of multiple time frequency resources for D2D communication from an evolved Node B (eNB);
Sensing the current D2D slot to determine if there is a transmit operation;
Sending a D2D transmission to the second UE at the beginning of the subsequent D2D slot, if the current D2D slot is not busy.
A method wherein multiple D2D transmissions to or from the second UE are grouped into multiple D2D slots with each D2D slot comprising multiple OFDM or SC-FDM symbols.
[Item 27]
Initiating a countdown with a selected number if the current D2D slot is not busy;
Decrementing the countdown after each non-busy D2D slot is detected, and suspending the countdown when a busy D2D slot is detected;
27. The method of clause 26, further comprising transmitting the D2D transmission to the second UE at the start of the next D2D slot after the countdown reaches zero.
[Item 28]
26. A method according to clause 26 or 27, further comprising the step of including in the D2D transmission a preamble for use by the second UE.
[Item 29]
29. A method according to any one of items 26 to 28, further comprising the step of including an encoded reservation time in the control channel identifying how many D2D slots are transmitted consecutively.
[Item 30]
30. The method according to any one of items 26 to 29, further comprising: interrupting detection of a plurality of D2D slots until the reservation time ends, when a reservation time is detected in the D2D slot.

Claims (21)

An apparatus of a UE configured to perform direct device-to-device (D2D) communication with one or more other user equipments (UEs),
The device
Transmitter and receiver circuits,
And processing circuit,
The processing circuit
Receive allocations of multiple resources for D2D communication from the eNode B (eNB);
Modulate control information for D2D transmission in multiple resource elements (multiple REs) of the physical D2D control channel according to single carrier frequency division multiplexing (SC-FDM) technology,
Modulate data for D2D transmission in multiple REs of physical D2D shared channel according to the SC-FDM technique,
Subjecting Hisage synchronization information for a plurality of the D2D transmission based on signaling on another device,
Generate a demodulation reference signal (DMRS) configured for demodulation of the physical D2D control channel and the physical D2D shared channel for transmissions in the plurality of resources allocated by the eNB for D2D communication Configured as
The apparatus wherein the plurality of REs of the physical D2D control channel and the plurality of REs of the physical D2D shared channel are within the plurality of resources allocated by the eNB for D2D communication.   The apparatus according to claim 1, wherein the plurality of REs of the physical D2D shared channel are determined according to a predetermined hopping pattern if frequency hopping is enabled. The UE is configured to include a cyclic prefix for the plurality of D2D transmissions,
The apparatus according to claim 1, wherein a length of the cyclic prefix for a plurality of the D2D transmissions is different from a length of a cyclic prefix used for a plurality of uplink transmissions to the eNB.   4. The apparatus of claim 3, wherein the length of the cyclic prefix for the plurality of D2D transmissions is less than the length of the cyclic prefix for the plurality of uplink transmissions.   5. The apparatus according to any one of the preceding claims, wherein the SC-FDM technique comprises modulation of multiple symbols on a single carrier frequency. The transmission / reception circuit can set transmission on a plurality of carrier frequencies according to orthogonal frequency division multiplexing technology, and can set transmission on a single carrier frequency according to SC-FDM technology,
The processing circuit sets a plurality of transmissions of a single carrier frequency to the transmission / reception circuit for the plurality of D2D transmissions, and sets a multicarrier transmission to the transmission / reception circuit to communicate with the eNB. The device according to any one of the preceding claims. The UE is further configured to receive D2D communication information from the eNB,
The apparatus according to claim 5, wherein the synchronization information is based on the D2D communication information received from the eNB.   The apparatus according to claim 5, wherein the synchronization information is derived from a plurality of signals received from the eNB.   The apparatus according to claim 5, wherein the synchronization information is based on signaling received from another UE.   The apparatus according to any one of the preceding claims, wherein the UE is further configured to transmit a preamble prior to the plurality of D2D transmissions.   11. Apparatus according to any one of the preceding claims, further comprising one or more antennas. Processing circuitry of the UE for establishing direct device-to-device (D2D) communication with the one or more other user equipments (UEs) to the UE,
Modulating control information for D2D transmission in multiple resource elements (multiple REs) of the physical D2D control channel according to single carrier frequency division multiplexing (SC-FDM) techniques;
Modulating data for D2D transmission in multiple REs of a physical D2D shared channel according to the SC-FDM technique;
And, if frequency hopping is enabled, performing a procedure of determining the plurality of REs of the physical D2D shared channel according to a predetermined hopping pattern;
The program, wherein the plurality of REs of the physical D2D control channel and the plurality of REs of the physical D2D shared channel are in a plurality of resources allocated by an extensible Node B (eNB) for D2D communication. In the processing circuit,
Receiving from the eNB the allocation of resources for D2D communication;
And instructions providing Hisage to other devices synchronization information for a plurality of the D2D transmission based on signaling received from the eNB,
Generating a demodulation reference signal (DMRS) configured for demodulation of the physical D2D control channel and the physical D2D shared channel for transmissions in the plurality of resources allocated by the eNB for the D2D communication The program according to claim 12, for further executing the procedure. The UE is configured to include a cyclic prefix for the plurality of D2D transmissions,
The program according to claim 12 or 13, wherein a length of the cyclic prefix for a plurality of the D2D transmissions is different from a length of a cyclic prefix used for a plurality of uplink transmissions to the eNB.   The program according to any one of claims 12 to 14, wherein the SC-FDM technique comprises modulation of multiple symbols on a single carrier frequency.   A computer readable storage medium storing the program according to any one of claims 12 to 15. An arrangement of user equipment (UE) configured for device-to-device (D2D) communication, comprising
The device
Transmitter and receiver circuits,
And processing circuit,
The processing circuit
Receive allocations of multiple resources for multiple D2D communication from the eNode B (eNB);
Decode multiple D2D transmissions from other UEs,
Receive synchronization information for the plurality of D2D transmissions based on signaling from the eNB;
Configured to receive a demodulation reference signal (DMRS) sent by the other UE in the plurality of resources allocated by the eNB for the plurality of D2D communications,
The plurality of D2D transmissions include a physical D2D control channel and a physical D2D shared channel,
The physical D2D control channel includes control information modulated according to single carrier frequency division multiplexing (SC-FDM) technology,
The physical D2D shared channel includes data modulated according to the SC-FDM technique,
The DMRS is configured for demodulation of the physical D2D control channel and demodulation of the physical D2D shared channel,
The apparatus wherein the physical D2D control channel and the physical D2D shared channel are within the plurality of resources allocated by the eNB for the plurality of D2D communications.   The apparatus according to claim 17, wherein if resource hopping is enabled, resource element (s) (RE) of the physical D2D shared channel are determined according to a predetermined hopping pattern. The UE is configured to decode a cyclic prefix that is part of the plurality of D2D transmissions,
The apparatus according to claim 17 or 18, wherein a length of the cyclic prefix is different from a length of a cyclic prefix used for multiple uplink transmissions to the eNB.   The apparatus according to any one of claims 17-19, further configured to receive multiple transmissions from the eNB according to a multi-carrier communication technique. The transmission / reception circuit can be configured to receive on a plurality of carrier frequencies according to orthogonal frequency division multiplexing technology, and can be configured to receive on a single carrier according to the SC-FDM technology,
The processing circuit sets the reception of a single carrier frequency for the plurality of D2D transmissions in the transmission / reception circuit, and sets the reception of multicarriers for a plurality of communications with the eNB in the transmission / reception circuit. 21. Apparatus according to any one of claims 17 to 20.

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